refactor: Improve Error Messaging for Export Collisions in Module Analysis

tests/functional/syntax/modules/test_exports.py

@@ -202,10 +202,9 @@ def foo():
     """
     input_bundle = make_input_bundle({"lib1.vy": lib1})
     with pytest.raises(NamespaceCollision) as e:
-        # TODO: make the error message reference the export
         compile_code(main, contract_path="main.vy", input_bundle=input_bundle)
 
-    assert e.value._message == "Member 'foo' already exists in self"
+    assert e.value._message == "Member 'foo' already exists in self (when exporting `lib1.foo`)"
 
     assert e.value.annotations[0].lineno == 4
     assert e.value.annotations[0].node_source_code == "lib1.foo"
@@ -235,7 +234,6 @@ def bar():
     """
     input_bundle = make_input_bundle({"lib1.vy": lib1})
     with pytest.raises(StructureException) as e:
-        # TODO: make the error message reference the export
         compile_code(main, contract_path="main.vy", input_bundle=input_bundle)
 
     assert e.value._message == "already exported!"
@@ -266,7 +264,6 @@ def bar():
     """
     input_bundle = make_input_bundle({"lib1.vy": lib1})
     with pytest.raises(StructureException) as e:
-        # TODO: make the error message reference the export
         compile_code(main, contract_path="main.vy", input_bundle=input_bundle)
 
     assert e.value._message == "already exported!"
@@ -300,7 +297,6 @@ def bar():
     """
     input_bundle = make_input_bundle({"lib1.vy": lib1})
     with pytest.raises(StructureException) as e:
-        # TODO: make the error message reference the export
         compile_code(main, contract_path="main.vy", input_bundle=input_bundle)
 
     assert e.value._message == "already exported!"

vyper/semantics/analysis/module.py

@@ -13,6 +13,7 @@
     InterfaceViolation,
     InvalidLiteral,
     InvalidType,
+    NamespaceCollision,
     StateAccessViolation,
     StructureException,
     UndeclaredDefinition,
@@ -565,7 +566,8 @@ def visit_ExportsDecl(self, node):
 
                 self._add_exposed_function(func_t, item, relax=False)
                 with tag_exceptions(item):  # tag exceptions with specific item
-                    self._self_t.typ.add_member(func_t.name, func_t)
+                    export_name = item.node_source_code
+                    self._self_t.typ.add_member_with_export_context(func_t.name, func_t, export_name)
 
                     exported_funcs.append(func_t)
 
@@ -588,7 +590,8 @@ def _add_exposed_function(self, func_t, node, relax=True):
         # call this before self._self_t.typ.add_member() for exception raising
         # priority
         if not relax and (prev_decl := self._all_functions.get(func_t)) is not None:
-            raise StructureException("already exported!", node, prev_decl=prev_decl)
+            export_name = node.node_source_code
+            raise StructureException(f"export `{export_name}` already exported!", node, prev_decl=prev_decl)
 
         self._all_functions[func_t] = node
 

vyper/semantics/types/module.py

@@ -366,6 +366,21 @@ def __init__(self, module: vy_ast.Module, name: Optional[str] = None):
         # allow `module.__interface__` (in type position)
         self._helper.add_member("__interface__", TYPE_T(self.interface))
 
+    def _check_add_member(self, name, export_context=None):
+        if (prev_type := self.members.get(name)) is not None:
+            if export_context:
+                msg = f"Member '{name}' already exists in {self} (when exporting `{export_context}`)"
+            else:
+                msg = f"Member '{name}' already exists in {self}"
+            raise NamespaceCollision(msg, prev_decl=prev_type.decl_node)
+
+    def add_member_with_export_context(self, name: str, type_: "VyperType", export_context: str = None) -> None:
+        """Add a member with optional export context for better error messages."""
+        from vyper.ast.identifiers import validate_identifier
+        validate_identifier(name)
+        self._check_add_member(name, export_context)
+        self.members[name] = type_
+
     # __eq__ is very strict on ModuleT - object equality! this is because we
     # don't want to reason about where a module came from (i.e. input bundle,
     # search path, symlinked vs normalized path, etc.)